LED light bulb and LED filament thereof

ABSTRACT

An LED filament and an LED light bulb applying the same are disclosed. The LED filament includes LED chips, conductive electrodes disposed corresponding to the LED chips, and a light conversion coating. The LED chips are electrically connected together and the conductive electrodes are electrically connected with the LED chips. The light conversion coating includes an adhesive and a plurality of phosphors. The light conversion coating coats on at least two sides of the LED chips and the conductive electrodes. The light conversion coating exposes a portion of two of the conductive electrodes. Accordingly, the LED filament is capable of emitting light similar to that a point light source does and the LED light bulb may emit omnidirectional light.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to the following Chinese PatentApplications No. CN 201510502630.3 filed on 2015 Aug. 17, CN201510966906.3 filed on 2015 Dec. 19, CN 201610041667.5 filed on 2016Jan. 22, CN 201610272153.0 filed on 2016 Apr. 27, CN 201610281600.9filed on 2016 Apr. 29, CN 201610394610.3 field on 2016 Jun. 3, and CN201610586388.7 filed on 2016 Jul. 22, the disclosures of which areincorporated herein in their entirety by reference.

TECHNICAL FIELD

The instant disclosure relates to illumination field, and moreparticularly, to an LED light bulb and an LED filament thereof.

RELATED ART

The LED has advantages of environmental protection, energy saving, highefficiency and long lifespan, and therefore it attracts widespreadattention in recent years and gradually replaces traditional lightinglamps. However, due that the luminescence of the LED has directivity,current LED lamps is unable to provide with an illumination with a wideangle range like traditional lamps. Accordingly, how to design LED lampswith similar wide range for illumination to the traditional lampschallenges the industries.

In order to provide with an illumination with a wide range, opticalcomponents like lenses, prisms, reflectors are utilized to adjust lightdistribution emitted originally from the LED. However, the opticalcomponents for adjusting the light distribution decrease the overalloptical efficiency of LED lamps. Consequently, how to improve theoptical efficiency and provide with wide range for illumination areimportant tasks in the lighting industry.

Next, an LED die without package can be deemed as a full-angle lightsource and is capable of providing with full-range illumination.However, the package of LED narrows the illumination angle and decreasesoptical efficiency.

Further, a lamp with a LED filament is more possible to providewide-range illumination and its outlook is closer to that of thetraditional incandescent (tungsten) light bulbs. This is also one ofadvantages of light bulb with a LED filament.

One of the challenges of LED light bulbs is omnidirectional lighting.Current LED light bulbs utilize LED filaments. The LED filament has LEDchips on a strip substrate and mixtures of silica gel with phosphorcoated on the LED chips. The substrate is usually a glass substrate or ametal substrate. The glass substrate has the advantages of not blockinglight emitted from LED chips; however, its disadvantages include thatthe thermal conductivity of the glass substrate is not good and theglass substrate is fragile. Likewise, the LED chips are disposed on themetal substrate having excellent thermal conductivity, but light emittedfrom the LED chips will be blocked from the metal substrate side.Additionally, the substrates of conventional LED filaments are hard andnot bendable. Accordingly, in order to provide with omnidirectionallighting, the conventional LED light bulb utilizes a number of LEDfilaments symmetrically positioned inside a bulb shell. The utilizationof multiple LED filaments increases the cost of the LED bulb because ofits complicated manufacturing processes, complex assembly procedures andlow yield rate. Additionally, the more LED filaments in a light bulb,the more soldering spots between filaments and filament supports thereare as well as the higher possibility soldering defects happens.

US patent publication number 20130058080A1 discloses an LED light bulband an LED light-emitting strip capable of emitting 4π (light. The LEDlight bulb comprises an LED light bulb shell, a core column with anexhaust tube and a bracket, at least one LED light emitting strip withLED chips therein emitting 4π (light, a driver, and an electricalconnector. The LED light bulb shell is vacuum sealed with the corecolumn so as to form a vacuum sealed chamber. The vacuum sealed chamberis filled with a gas having a low coefficient of viscosity and a highcoefficient of thermal conductivity. The bracket and the LED lightemitting strips fixed on the bracket are housed in the vacuum sealedchamber. The LED light emitting strip is in turn electrically connectedto the driver, the electrical connector, while the electrical connectoris used to be electrically connected to an external power supply, so asto light the LED light emitting strips.

SUMMARY

To address the issues, the instant disclosure provides with embodimentsof an LED filament, a manufacturing method therefor, and an LED lightbulb utilizing the LED filament.

According to an embodiment, an LED filament comprising a plurality ofLED chips, at least two conductive electrodes disposed corresponding tothe plurality of LED chips, and a light conversion coating. Theplurality of LED chips and the conductive electrodes are electricallyconnected therebetween. The light conversion coating comprises anadhesive and a plurality of phosphors. The light conversion coatingcoats on at least two sides of the LED chips and the conductiveelectrodes. The light conversion coating exposes a portion of two of theconductive electrodes. The phosphors in the light conversion coating arecapable of emitting light after absorbing some form of radiation.

According to an embodiment, the LED filament further comprises aplurality of conductive wires electrically and correspondingly connectedamong the plurality of LED chips and the conductive electrodes. Thelight conversion coating covers the plurality of conductive wires.

According to an embodiment, the LED filament further comprises aplurality of circuit films electrically and correspondingly connectedamong the plurality of LED chips and the conductive electrodes. Thelight conversion coating covers the plurality of the circuit films.

According to an embodiment, each of the circuit films comprises a firstfilm and a conductive circuit disposed thereon. The conductive circuitsare electrically and correspondingly connected among the plurality ofLED chips and the conductive electrodes.

According to an embodiment, the light conversion coating comprises abase layer and a top layer. The plurality of LED chips is on a side ofthe base layer. The Shore D Hardness of the base layer is at least 60HD.

According to an embodiment, the light conversion coating furthercomprises oxidized nanoparticles. The size of the oxidized nanoparticlesis substantially smaller than the size of the phosphors.

According to an embodiment, the Young's Modulus of the LED filament isbetween 0.1×10¹⁰ Pa to 0.3×10¹⁰ Pa. The composition ratio of theplurality of the phosphors to the adhesive is between 1:1 and 99:1.

According to an embodiment, an LED light bulb comprises a bulb shell, abulb base connected with the bulb shell, at least two conductivesupports disposed in the bulb shell, and a single LED filament disposedin the light bulb. The LED filament comprises a plurality of LED chips,at least two conductive electrodes disposed corresponding to theplurality of LED chips, and a light conversion coating. The plurality ofLED chips and the conductive electrodes are electrically connectedtherebetween. The conductive electrodes are electrically andrespectively connected with the conductive supports. The lightconversion coating coats on at least two sides of the LED chips and theconductive electrodes. The light conversion coating exposes a portion oftwo of the conductive electrodes. The light conversion coating comprisesan adhesive and a plurality of phosphors.

According to an embodiment, the LED light bulb further comprises a stemin the bulb shell and a heat dissipating element between the bulb shelland bulb base. The heat dissipating element is connected with the stem.The LED filament connected with the stem.

According to some embodiments, each of the surfaces of the LED chips iscovered by the light conversion coating. The phosphors of lightconversion coating may absorb light out of the surfaces of the LED chipsand emit light with longer wavelength. Since the LED chips aresurrounded by the light conversion coating to form the main body of theLED filament, the LED filament is capable of emitting light from thesides of the filament having the light conversion coating, and beingbended with adequate rigidity. The LED light bulb is capable of emittingomnidirectional light with the single LED filament.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of an LED light bulb with partialsectional view according to a first embodiment of the LED filament;

FIG. 2 illustrates a partial cross-sectional view at section 2-2 of FIG.1;

FIGS. 3A and 3B illustrate disposition of the metal electrodes and theplurality of LED chips according to other embodiments of the LEDfilament;

FIG. 4 illustrates a perspective view of an LED filament with partialsectional view according to a second embodiment of the presentdisclosure;

FIG. 5 illustrates a partial cross-sectional view at section 5-5 of FIG.4;

FIG. 6A illustrates a first embodiment of the uncut circuit filmaccording to the second embodiment of the LED filament;

FIG. 6B illustrates the alignment between the LED chips and the firstembodiment of the uncut circuit film of FIG. 6A;

FIG. 7A illustrates a second embodiment of the uncut circuit filmaccording to the second embodiment of the LED filament;

FIG. 7B illustrates the alignment between the LED chips and the secondembodiment of the uncut circuit film of FIG. 7A;

FIG. 8A illustrates a third embodiment of the uncut circuit filmaccording to the second embodiment of the LED filament;

FIG. 8B illustrates the alignment between the LED chips and the thirdembodiment of the uncut circuit film of FIG. 8A;

FIGS. 9A to 9E illustrate a manufacturing method of an LED filamentaccording to a first embodiment of the present disclosure;

FIG. 10 illustrates a manufacturing method of an LED filament accordingto a second embodiment of the present disclosure;

FIGS. 11A to 11E illustrate a manufacturing method of an LED filamentaccording to a third embodiment of the present disclosure;

FIGS. 12A and 12B illustrate a perspective view of an LED light bulbaccording to a first and a second embodiments of the present disclosure;

FIG. 13A illustrates a perspective view of an LED light bulb accordingto a third embodiment of the present disclosure;

FIG. 13B illustrates an enlarged cross-sectional view of the dashed-linecircle of FIG. 13A;

FIG. 14A illustrates a cross-sectional view of an LED light bulbaccording to a fourth embodiment of the present disclosure; and

FIG. 14B illustrates the circuit board of the driving circuit of the LEDlight bulb according to the fourth embodiment of the present disclosure.

DETAILED DESCRIPTION

The instant disclosure provides an LED filament and an LED light bulb tosolve the abovementioned problems. The instant disclosure will now bedescribed more fully hereinafter with reference to the accompanyingdrawings, in which exemplary embodiments of the disclosure are shown.This disclosure may, however, be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein.Rather, these embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the scope of the disclosureto those skilled in the art. Like reference numerals refer to likeelements throughout.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” or “includes” and/or “including” or “has” and/or“having” when used herein, specify the presence of stated features,regions, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof.

It will be understood that the term “and/or” includes any and allcombinations of one or more of the associated listed items. It will alsobe understood that, although the terms first, second, third etc. may beused herein to describe various elements, components, regions, partsand/or sections, these elements, components, regions, parts and/orsections should not be limited by these terms. These terms are only usedto distinguish one element, component, region, part or section fromanother element, component, region, layer or section. Thus, a firstelement, component, region, part or section discussed below could betermed a second element, component, region, layer or section withoutdeparting from the teachings of the present disclosure.

The following description with reference to the accompanying drawings isprovided to explain the exemplary embodiments of the disclosure. Notethat in the case of no conflict, the embodiments of the presentdisclosure and the features of the embodiments may be arbitrarilycombined with each other.

As indicated in the section of the cross-reference, the instantdisclosure claims priority of several Chinese patent applications, andthe disclosures of which are incorporated herein in their entirety byreference. When it comes to claim construction, the claims,specification, and prosecution history of the instant disclosurecontrols if any inconsistency between the instant disclosure and theincorporated disclosures exists.

Please refer to FIGS. 1 and 2. FIG. 1 illustrates a perspective view ofan LED filament with partial sectional view according to a firstembodiment of the present disclosure while FIG. 2 illustrates a partialcross-sectional view at section 2-2 of FIG. 1. According to the firstembodiment, the LED filament 100 comprises a plurality of LED chips 102,104, at least two conductive electrodes 110, 112, and a light conversioncoating 120. The conductive electrodes 110, 112 are disposedcorresponding to the plurality of LED chips 102, 104. The LED chips 102,104 are electrically connected together. The conductive electrodes 112,114 are electrically connected with the plurality of LED chips 102, 104.The light conversion coating 120 coats on at least two sides of the LEDchips 102, 104 and the conductive electrodes 110, 112. The lightconversion coating 120 exposes a portion of two of the conductiveelectrodes 110, 112. The light conversion coating 120 comprises anadhesive 122 and a plurality of phosphors 124.

LED filament 100 emits light while the conductive electrodes 110, 112are applied with electrical power (electrical current sources orelectrical voltage sources). In this embodiment, the light emitted fromthe LED filament 100 is substantially close to 360 degrees light likethat from a point light source. An LED light bulb 10 a, 10 b,illustrated is in FIGS. 12A and 12B, utilizing the LED filament 100 iscapable of emitting omnidirectional light, which will be described indetailed in the followings.

As illustrated in the FIG. 1, the cross-sectional outline of the LEDfilament 100 is rectangular. However, the cross-sectional outline of theLED filament 100 is not limited to rectangular, but may be triangle,circle, ellipse, square, diamond, or square with chamfers.

Each of LED chips 102, 104 may comprise a single LED die or a pluralityof LED dies. The outline of the LED chip 102, 104 may be, but notlimited to, a strip shape which does not have the problem of currentdiffusion uniform distribution. Therefore, extended electrodes are notrequired on the electrodes of the LED chip 102, 104 to help the currentdiffusion. The extended electrodes may shield the illumination of theLED chip, thereby affecting the illumination efficiency. In addition,the LED chips 102, 104 may be coated on their surfaces with a conductiveand transparent layer of Indium Tim Oxide (ITO). The metal oxide layercontributes to uniform distribution of the current diffusion and toincrease of illumination efficiency. Specifically, the aspect ratio ofthe LED chip may be 2:1 to 10:1; for example, but not limited to, 14×28or 10×20. Further, the LED chips 102, 104 may be high power LED dies andare operated at low electrical current to provide sufficientillumination but less heat.

The LED chips 102, 104 may comprise sapphire substrate or transparentsubstrate. Consequently, the substrates of the LED chips 102, 104 do notshield/block light emitted from the LED chips 102, 104. In other words,the LED chips 102, 104 are capable of emitting light from each side ofthe LED chips 102, 104.

The electrical connections among the plurality of LED chips 102, 104 andthe conductive electrodes 112, 114, in this embodiment, may be shown inFIG. 1. The LED chips 102, 104 are connected in series and theconductive electrodes 112, 114 are disposed on and electrically andrespectively connected with the two ends of the series-connected LEDchips 102, 104. However, the connections between the LED chips 102, 104are not limited to that in FIG. 1. Alternatively, the connections may bethat two adjacent LED chips 102, 104 are connected in parallel and thenthe parallel-connected pairs are connected in series.

According to this embodiment, the conductive electrodes 110, 112 may be,but not limited to, metal electrodes. The conductive electrodes 110, 112are disposed at two ends of the series-connected LED chips 102, 104 anda portion of each of the conductive electrodes 110, 112 are exposed outof the light conversion coating 120. In an embodiment of at least threeconductive electrodes 110, 112, a portion of two of the conductiveelectrodes 110, 112 are exposed out of the light conversion coating 120.Please refer to FIGS. 3A and 3B which illustrate disposition of metalelectrodes and a plurality of LED chips according to other embodimentsof the LED filament. In the embodiment of FIG. 3A, the LED chips 102,104 are connected in series and the two ends of the series-connected LEDchips 102, 104 are positioned at the same side of the LED filament 100to form an U shape. Accordingly, the two conductive electrodes 110, 112are positioned at the same side as the ends of the series-connected LEDchips 102, 104. According to the embodiment of FIG. 3B, the LED chips102, 104 are disposed along two parallel LED strips and the LED chips102, 104 along the same LED strip are connected in series. Twoconductive electrodes 110, 112 are disposed at two ends of theseries-connected LED chips 102, 104 and electrically connected to eachof ends of the series-connected LED chips 102, 104. In this embodimentof FIG. 3B, there are, but not limited to, only two conductiveelectrodes 110, 112. For examples, the LED filament 100, in practices,may comprise four sub-electrodes. The four sub-electrodes are connectedto four ends of the series-connected LED chips 102, 104, respectively.The sub-electrodes may be connected to anode and ground as desired.Alternatively, one of two conductive electrodes 110, 112 may be replacedwith two sub-electrodes, depending upon the design needs.

Please further refer to FIG. 12A. The conductive electrodes 110, 112 hasthrough holes 111, 113 (shown in FIG. 1) on the exposed portion forbeing connected with the conductive supports 14 a, 14 b of the LED lightbulb 10 a.

Please refer to FIGS. 1 and 2 again. According to this embodiment, theLED filament 100 further comprises conductive wires 140 for electricallyconnecting the adjacent LED chips 102, 104 and conductive electrodes110, 112. The conductive wires 140 may be gold wires formed by a wirebond of the LED package process, like Q-type. According to FIG. 2, theconductive wires 140 are of M shape. The M shape here is not to describethat the shape of the conductive wires 140 exactly looks like letter M,but to describe a shape which prevents the wires from being tight andprovides buffers when the conductive wires 140 or the LED filament 100is stretched or bended. Specifically, the M shape may be any shapeformed by a conductive wire 140 whose length is longer than the lengthof a wire which naturally arched between two adjacent LED chips 102,104. The M shape includes any shape which could provide buffers whilethe conductive wires 104 are bended or stretched.

The light conversion coating 120 comprises adhesive 122 and phosphors122. The light conversion coating 120 may, in this embodiment, wrap orencapsulate the LED chips 102, 104 and the conductive electrodes 110,112. In other words, in this embodiment, each of six sides of the LEDchips 102, 104 is coated with the light conversion coating 120;preferably, but not limited to, is in direct contact with the lightconversion coating 120. However, at least two sides of the LED chips102, 104 may be coated with the light conversion coating 120.Preferably, the light conversion coating 120 may directly contact atleast two sides of the LED chips 102, 104. The two directly-contactedsides may be the major surfaces which the LED chips emit light.Referring to FIG. 1, the major two surfaces may be the top and thebottom surfaces. In other words, the light conversion coating 120 maydirectly contact the top and the bottom surfaces of the LED chips 102,104 (upper and lower surfaces of the LED chips 102, 104 shown in FIG.2). Said contact between each of six sides of the LED chips 102, 104 andthe light conversion coating 120 may be that the light conversioncoating 120 directly or indirectly contacts at least a portion of eachside of the LED chips 102, 104. Specifically, one or two sides of theLED chips 102, 104 may be in contact with the light conversion coating120 through die bond glue. In some embodiments, the die bond glue may bemixed with phosphors to increase efficiency of light conversion. The diebond glue may be silica gel mixed with silver powder or heat dissipatingpowder to increase effect of heat dissipation thereof. The adhesive 122may be silica gel. In addition, the silica gel may be partially ortotally replaced with polyimide or resin materials to improve thetoughness of the light conversion coating 120 and to reduce possibilityof cracking or embrittlement.

The phosphors 124 of the light conversion coating 120 absorb some formof radiation to emit light. For instance, the phosphors 124 absorb lightwith shorter wavelength and then emit light with longer wavelength. Inone embodiment, the phosphors 124 absorb blue light and then emit yellowlight. The blue light which is not absorbed by the phosphors 124 mixeswith the yellow light to form white light. According to the embodimentwhere six sides of the LED chips 102, 104 are coated with the lightconversion coating 120, the phosphors 124 absorb light with shorterwavelength out of each of the sides of the LED chips 102, 104 and emitlight with longer wavelength. The mixed light (longer and shorterwavelength) is emitted from the outer surface of the light conversioncoating 120 which surrounds the LED chips 102, 104 to form the main bodyof the LED filament 100. In other words, each of sides of the LEDfilament 100 emits the mixed light.

The light conversion coating 120 may expose a portion of two of theconductive electrodes 110, 112. Phosphors 124 is harder than theadhesive 122. The size of the phosphors 124 may be 1 to 30 um(micrometer) or 5 to 20 um. The size of the same phosphors 124 aregenerally the same. In FIG. 2, the reason why the cross-sectional sizesof the phosphors 124 are different is the positions of the cross-sectionfor the phosphors 124 are different. The adhesive 122 may betransparent, for example, epoxy resin, modified resin or silica gel, andso on.

The composition ratio of the phosphors 124 to the adhesive 122 may be1:1 to 99:1, or 1:1 to 50:1. The composition ratio may be volume ratioor weight ratio. Please refer to FIG. 2 again. The amount of thephosphors 124 is greater than the adhesive 122 to increase the densityof the phosphors 124 and to increase direct contacts among phosphors124. The arrow lines on FIG. 2 show thermal conduction paths from LEDchips 102, 104 to the outer surfaces of the LED filament 100. Thethermal conduction paths are formed by the adjacent and contactedphosphors. The more direct contacts among the phosphors 124, the morethermal conduction paths forms, the greater the heat dissipating effectthe LED filament 100 has, and the less the light conversion coatingbecomes yellow. Additionally, the light conversion rate of the phosphors124 may reach 30% to 70% and the total luminance efficiency of the LEDlight bulb 10 a, 10 b is increased. Further, the hardness of the LEDfilament 100 is increased, too. Accordingly, the LED filament 100 maystand alone without any embedded supporting component like rigidsubstrates. Furthermore, the surfaces of cured LED filament 100 are notflat due to the protrusion of some of the phosphors 124. In other words,the roughness of the surfaces and the total surface area are increased.The increased roughness of the surfaces improves the amount of lightpassing the surfaces. The increased surface area enhances the heatdissipating effect. As a result, the overall luminance efficiency of theLED light filament 100 is raised.

Next, LED chips 102, 104 may comprise LED dies which emit blue light.The phosphors 124 may be yellow phosphors (for example Garnet seriesphosphors, YAG phosphors), so that the LED filament 100 may emit whitelight. In practices, the composition ratio of phosphors 124 to theadhesive 122 may be adjusted to make the spectrum of the white lightemitted from the LED filament 100 closer to that emitted fromincandescent bulbs. Alternatively, the phosphors 124 may be powderswhich absorb blue light (light with shorter wavelength) and emit yellowgreen light (hereinafter referred to yellow green powders) or emit redlight (hereinafter referred to red powders) (light with longerwavelength). The light conversion coating 120 may comprise less redpowders and more yellow green powders, so that the CCT (corrected colortemperature) of the light emitted from the LED filament 100 may close to2,400 to 2,600 K (incandescent light).

As mention above, a desired deflection of the LED filament 100 may beachieved by the adjustment of the ratio of phosphors 124 to the adhesive122. For instance, the Young's Modulus (Y) of the LED filament 100 maybe between 0.1×10¹⁰ to 0.3×10¹⁰ Pa. If necessary, the Young's Modulus ofthe LED filament 100 may be between 0.15×10¹⁰ to 0.25×10¹⁰ Pa.Consequently, the LED filament 100 would not be easily broken and stillpossess adequate rigidity and deflection.

Please refer to FIGS. 4 to 5. FIG. 4 illustrates a perspective view ofan LED light bulb with partial sectional view according to a secondembodiment of the LED filament and FIG. 5 illustrates a partialcross-sectional view at section 5-5 of FIG. 4.

According to the second embodiment of the LED filament 200, the LEDfilament 200 comprises a plurality of LED chips 202, 204, at least twoconductive electrodes 210, 212, and a light conversion coating 220. Theconductive electrodes 210, 212 are disposed corresponding to theplurality of LED chips 202, 204. The plurality of LED chips 202, 204 andthe conductive electrodes 212, 214 are electrically connectedtherebetween. The light conversion coating 220 coats on at least twosides of the LED chips 202, 204 and the conductive electrodes 210, 212.The light conversion coating 220 exposes a portion of two of theconductive electrodes 210, 212. The light conversion coating 220comprises an adhesive 222, a plurality of inorganic oxide nanoparticles226 and a plurality of phosphors 224.

The size of the plurality of inorganic oxide nanoparticles 226 is around10 to 300 nanometers (nm) or majorly is around 20 to 100 nm. The size ofthe plurality of inorganic oxide nanoparticles 226 is lesser than thatof the phosphors 224. The plurality of the inorganic oxide nanoparticles226 may be, but not limited to, aluminium oxides (Al₂O₃), silicon oxide(SiO₂), zirconium oxide (Zirconia, ZrO₂), titanic oxide (TiO₂), Calciumoxide (CaO), strontium oxide (SrO), and Barium oxide (BaO).

As shown in FIG. 5, the inorganic oxide nanoparticles 226 and thephosphors 224 are mixed with the adhesive 222. The unit prices and thehardnesses of the inorganic oxide nanoparticles 226 and the phosphors224 are different. Therefore, a desired deflection, thermalconductivity, hardness, and cost of the LED filament 200 may be reachedby adjustment of the ratio of the adhesive 222, phosphors 224 to theinorganic oxide nanoparticles 226 affects. In addition, due that thesize of the inorganic oxide nanoparticles 226 is lesser than that of thephosphors 224, the inorganic oxide nanoparticles 226 may fill into thegaps among the phosphors 224. Hence, the contact area among thephosphors 224 and the inorganic oxide nanoparticles 226 is increased andthermal conduction paths are increased as shown by arrow lines on FIG.5, too. Further, the inorganic oxide nanoparticles 226 may deflect orscatter light incident thereon. The light deflection and scattering makethe light emitted from phosphors 224 mixed more uniformly and thecharacteristics of the LED filament 200 becomes even better.Furthermore, the impedance of the inorganic oxide nanoparticles 226 ishigh and no electrical leakage would happen through the inorganic oxidenanoparticles 226.

In some embodiments, the phosphors 224 are substantially uniformlydistributed in the adhesive 222 (for instance, in silica gel, thepolyimide or resin materials). Each of the phosphors 224 may bepartially or totally wrapped by the adhesive 222 to improve the crackingor embrittlement of the light conversion coating 220. In the case thatnot each of the phosphors 224 is totally wrapped by the adhesive 222,the cracking or embrittlement of the light conversion coating 220 isstill improved. In some embodiments, silica gel may be mixed with thepolyimide or resin materials to form the light conversion coating 220.

The LED filament 200 further comprises a plurality of circuit film 240(or call as transparent circuit film) for electrically andcorrespondingly connected among the plurality of LED chips and theconductive electrodes. Specifically, the plurality of circuit film 240is electrically connecting the adjacent LED chips 202, 204 andconductive electrodes 210, 212. The light conversion coating 220 mayencapsulate the plurality of circuit film 240.

Please refer to FIG. 6A. FIG. 6A illustrates a first embodiment of theuncut circuit film according to the second embodiment of the LEDfilament 200. Each of the circuit films 240 comprises a first film 242and a conductive circuit 244 disposed on the first film 242. The firstfilm 242 in one embodiment may be, but not limited to, a thin film. Inorder to be easily understood the embodiments, the following descriptionuses thin film as an example for the first film 242. However, the thinfilm 242 is not the only embodiment for the first film 242. The thinfilm 242 may be a transparent or translucent film. The transparent filmmay allow light emitted from the LED chips 202, 204 and/or phosphors 124to pass. The conductive circuits 244 are electrically andcorrespondingly connected among the plurality of LED chips 202, 204 andthe conductive electrodes 210, 212. In this embodiment, the conductivecircuits 244 are of bar shape and substantially parallel to each other.However, the conductive circuits 244 may be in other shape or pattern.Please refer to FIG. 7A which illustrates a second embodiment of theuncut circuit film according to the second embodiment of the LEDfilament. Each of the circuit films 240 a comprises a thin film 242 aand a conductive circuit 244 a disposed on the thin film 242 a. Theconductive circuits 244 a are substantially parallel lines electricallyconnected with pads of adjacent LED chips 202, 204 as shown in FIG. 7B.Please refer to FIG. 8A which illustrates a third embodiment of theuncut circuit film according to the second embodiment of the LEDfilament. Each of the circuit films 240 b comprises a thin film 242 band a conductive circuit 244 b disposed on the thin film 242 b. Theconductive circuits 244 b are crossover lines electrically connectedwith pads of adjacent LED chips 202 b, 204 b as shown in FIG. 8B. Thewidth of the lines may be 10 micrometers (um) and the thickness of thelines may be 2 um. The pattern or shape of the conductive circuits 244,244 a, 244 b are not limited to the above-mentioned embodiments, anypattern or shape which is capable of connecting pads of adjacent LEDchips 202, 204 and conductive electrodes 210, 212 are feasible.

The thin film 242 may be, but not limited to, Polyimide film (PI film).Transmittance of the polyimide film is above 92%. The material of theconductive circuit 244 may be, but not limited to, indium tin oxide(ITO), nano-silver plasma, metal grids, or nano-tubes. The advantages ofSilver include good reflection and low light absorption. Nano-scaledsilver lines in grid shape have advantages of low resistance and highpenetration of light. In addition, gold-dopped nano-silver lines mayenhance the adherence between the pads of the LED chips 202, 204 and thesliver lines (conductive circuits).

Please refer to FIG. 6A again. The circuit film 240 may be made byfirstly forming conductive circuits 244 on a thin film 242, and thenforming slots 246 on the thin film 242 with the conductive circuits 244.

Please refer to FIG. 6A. The conductive circuits 244 do not cover thewhole surface of the thin film 242. Consequently, light emitted from theLED chips 202, 204 can pass through the circuit film 240 at least fromthe portion of the thin film 242 where the conductive circuits 244 donot occupy. In the second embodiment, the circuit film 240 is used toelectrically connect with adjacent LED chips 202, 204 and the conductiveelectrodes 210, 212. The circuit film 240 has the advantages of widerconductive lines, better deflection, and better toughness (lesspossibility of being broken) than the conductive wires 140 in the firstembodiments.

Regarding the electrical connection among the circuit film 240, LEDchips 202, 204, and the conductive electrodes 210, 212, conductive gluesmay be applied on the surfaces of the LED chips 202, 204 and theconductive electrodes 210, 212 where the conductive circuits 244 aregoing to electrically connect. The conductive glues may be, but notlimited to, silver paste, solder paste (tin paste), or conductive gluesdoped with conductive particles. Then, dispose the circuit film 240 onthe LED chips 202, 204 and the conductive electrodes 210, 212 withadequate alignment and cure the circuit film 240 and the conductiveglues by heat or UV.

Please refer to FIGS. 9A to 9E which illustrate a manufacturing methodof an LED filament according to a first embodiment. The manufacturingmethod of the LED filament 200 comprises:

S20: dispose LED chips 202, 204 and at least two conductive electrodes210, 210 on a carrier 280, referring to FIG. 9A;

S22: electrically connect the LED chips 202, 204 with the conductiveelectrodes 210, 212, referring to FIG. 9B; and

S24: dispose a light conversion coating 220 on the LED chips 202, 204and the conductive electrodes 210, 212. The light conversion coating 220coats on at least two sides of the LED chips 202, 204 and the conductiveelectrodes 210, 212. The light conversion coating 220 exposes a portionof at least two of the conductive electrodes 210, 212. The lightconversion coating 220 comprises adhesive 222 and a plurality ofphosphors 224, referring to FIGS. 9C to 9E.

In S20, the plurality of LED chips 202, 204 are disposed in arectangular array. Each column of the LED chips 202, 204, at the end ofthe manufacturing process, may be cut into a single LED filament 200.During disposition of the LED chips 202, 204, the anodes and cathodes ofthe LED chips 202, 204 should be properly orientated for later connectedin series or parallel. The carrier 280 may be, but not limited to, glasssubstrate or metal substrate. The carrier 280 may be, but not limitedto, a plate like that shown in FIG. 9A, or a plate with a groove likethe carrier 180 shown in FIG. 10. The groove is for being disposed withthe base layer 120 b.

In S22, the uncut circuit film 240 a is similar to the circuit film 240a shown in FIG. 7A. The LED chips 202, 204 and the conductive circuit210, 212 are electrically connected by the parallel conductive lines.Alternatively, the circuit film 240, 240 b shown, respectively, in FIG.6A or 8A may be used in S22. The conductive wires 140 shown in FIG. 2can be used in S22, too.

In S24, the light conversion coating 220 may be coated on the LED chips202, 204 and the conductive electrodes 210, 212 by different method.Firstly, taking FIGS. 9C to 9E as an example, the manufacturing methodof S24 comprises:

S240: coat a light conversion sub-layer (top layer 220 a) on a surfaceof the LED chips 202, 204 and the conductive electrodes 210, 212 whichis not contact with the carrier 280;

S242: flip over the LED chips 202, 204 and the conductive electrodes210, 212 disposed with the top layer 220 a; and

S244: coat a light conversion sub-layer (base layer 220 b) on a surfaceof the LED chips 202, 204 and the conductive electrodes 210, 212 whichare not coated with the top layer 220 a.

In order to distinguish the light conversion sub-layers in S240 and inS244, the light conversion sub-layer in S240 is referred to top layer220 a and the light conversion sub-layer in S244 is referred to baselayer 220 b hereinafter.

In S240, after the LED chips 202, 204 and the conductive electrodes 210,212 are coated with the top layer 220 a, the adhesive 222 and thephosphors 224 will fill out the gaps among the LED chips 202, 204 andthe conductive electrodes 210, 212. Then, proceed with a curing processto harden the top layer which encapsulates the upper part of the LEDchips 202, 204 and the conductive electrodes 210, 212 and exposes aportion of at least two of the conductive electrodes 210, 212. Thecuring process may be done by heat or UV.

In S242, the flip-over of the semi-finished piece may be done by twodifferent ways in accordance with different situations. Concerning thefirst flip-over way, the LED chips 202, 204 and the conductiveelectrodes 210, 212 are disposed on the carrier 280 without anyadherences with the carrier 280. S242 can be done by flip the curedsemi-finished piece over directly. Then, place the flipped-oversemi-finished piece on the carrier 280 again. (The semi-finished pieceis the cured the LED chips 202, 204 and the conductive electrodes 210,212 covered with the top layer 220 a.)

As for the second way, glues are applied on the carrier 280. The gluesare, for instance, photoresist in semiconductor process, or die bondglues. The glues (photoresist or die bond glues) is for temporarilyfixing the LED chips 202, 204 and the conductive electrodes 210, 212 onthe carrier 280. The glue may be removed by acetone or solvent and thesemi-finished piece is separated from the carrier 280. If necessary, theremained glues may be removed by an additional cleaning process.

In S244, referring to FIG. 9E, cure the base layer 220 b after the baselayer 220 b is coated on the surface of the LED chips 202, 204 and theconductive electrodes 210, 212.

Referring to FIG. 9C, the top layer 220 a is slightly greater than theuncut circuit film 240 a. However, it is not a requirement. The sizes ofthe top layer 220 a may be the same as or lesser than that of the uncutcircuit film 240 a. Referring to FIG. 9E, the area of the top layer 220a is substantially the same as that of the base layer 220 b. It is not arequirement, either. In implementation, the area of the top layer 220 amay be greater or lesser than the area of the base layer 220 b. FIG. 9Eillustrates a semi-finished LED filament where a plurality of LEDfilaments 200 are integrated into one piece.

After S24, the method may further comprise S26: cut the semi-finishedLED filament along the dot-and-dash lines shown in FIG. 9E. Each cutportion is an LED filament 200. The semi-finished LED may be cut everyother two dot-and-dash lines.

FIGS. 6B, 7B and 8B illustrate uncut circuit films 240, 240 a, 240 b ofFIGS. 6A, 7A and 8A covering the LED chips 202, 204 and the conductiveelectrodes 210, 212 with proper alignment.

The method of FIGS. 9A to 9E illustrates each LED filament are disposedin a rectangular array manner. Alternatively, the disposition of S20 maybe a single column of LED chips 202, 204. In the consequence, S26 may beomitted.

Please refer to FIG. 10 for the second embodiment of the manufacturingmethod for the LED filament 200. The method comprises:

S20A: coat a light conversion sub-layer (a base layer 120 b) on acarrier 180;

S20B: dispose LED chips 102, 104 and conductive electrodes 110, 112 onthe base layer 120 b;

S22: electrically connect the LED chips 102, 104 with the conductiveelectrodes 110, 112; and

S24: coat a light conversion sub-layer (top layer 120 a) on the LEDchips 102, 104 and the conductive electrodes 110, 112. The top layer 120a coats on the LED chips 102, 104 and the conductive electrodes 110,112. The top layer 120 a and the base layer 120 b expose a portion of atleast two of the conductive electrodes 110, 112. The light conversioncoating 120 (top layer 120 a and the base layer 120 b) comprisesadhesive 122 and a plurality of phosphors 124.

As shown in FIG. 10, the base layer 120 b is a part of the lightconversion coating 120 and comprises an adhesive 122 and phosphors 124.In the embodiment of FIG. 10, the base layer 120 b is, but not limitedto, coated on the carrier 180 with a groove. Alternatively, the carrier180 can be omitted. In other words, the base layer 120 b may be place ona work table without any carrier 180. The LED chips 102, 104 and theconductive electrodes 110, 112 are disposed on the base layer 120 b.

The thickness of the base layer 120 b may be 50 to 100 um. Thecomposition ratio of phosphors 124 to the adhesive 122 can be adjustedand the thickness of the base layer 120 b may be around 60 to 80 um.After S20, a pre-curing process may be used to slightly cure the baselayer 120 b so that the LED chips 102, 104 and the conductive electrodes110, 112 can be fixed on the base layer 120 b. Besides, the LED chips102, 104 and the conductive electrodes 110, 112 may be fixed on the baselayer 120 b by die bond glues.

After the electrical connection of S22, the top layer 120 a is coated onthe LED chips 102, 104 and the conductive electrodes 110, 112 and then acuring process is proceeded with to cure the top layer 120 a.Consequently, the flip-over of S242 and glue-removing process areomitted.

According to the embodiment of FIG. 10, after S24, the process of S26may be proceeded with.

The base layer 120 b is used for carrying the LED chips 102, 104 and theconductive electrodes 110, 112 and its thickness may be 0.5 to 3minimeters (mm) or 1 to 2 mm.

The composition ratio of phosphors 124 to the adhesive 122 may beadjusted accordingly to make the base layer 120 b hard enough tosufficiently carry the LED chips 102, 104 and the conductive electrodes110, 112 and for the following process like wire bond. The Shore DHardness of the base layer 120 b may be at least 60 HD. Hence, theoverall LED filament 10 a will have enough hardness, rigidity anddeflection. The electrical conductivity of the connection among the LEDchips 102, 104 and the conductive electrodes 110, 112 can be maintainedeven though the LED filament 10 a is bent.

In accordance with the embodiment of FIG. 10, the hardness of the curedbase layer 120 b is better to be sufficient to carry the LED chips 102,104 and the conductive electrodes 110, 112 and to support for the wirebonding process. However, the top layer 120 a is not required to havethe same hardness as the base layer 120 b. Accordingly, the adjustmentof ratio of the phosphors 124 to the adhesive 122 is more flexible.Alternatively, the light conversion coating 120 may comprise inorganicoxide nanoparticles 224 (not shown in FIG. 10).

Next, please refer to FIGS. 11A to 11D which illustrate a manufacturingmethod of an LED filament according to a third embodiment. Themanufacturing method for an Led filament 10 a comprises:

S202: dispose conductive foil 130 on a light conversion sub-layer (baselayer 120 b), referring to FIG. 11A;

S204: dispose a plurality of LED chips 102, 104 and a plurality ofconductive electrodes 110,112 on the conductive foil 130, referring toFIG. 11B;

S22: electrically connect the LED chips 102, 104 with the conductiveelectrodes 110, 112, referring to FIG. 11C; and

S24: coat a light conversion sub-layer (top layer 120 a) on the surfacesof the LED chips 102, 104 and the conductive electrode 110, 112 whereare not in contact with the base layer 120 b. The light conversioncoating 120 (including the base layer 120 b and the top layer 120 a)coats on at least two sides of the LED chips 102, 104 and the conductiveelectrodes 110, 112. The light conversion coating 120 exposes a portionof at least two of the plurality of conductive electrodes 110, 112. Thelight conversion coating 120 comprises adhesive 122 and phosphors 124.

Please refer to FIG. 11A, the light conversion coating of S202 is calledas the base layer 120 b. The conductive foil 130 may have a plurality ofopenings 132. The width of each of the openings 132 may be lesser thanthe length of the LED chips 102, 104 and each of the openings 132 isaligned with the portion of the LED chips 102, 104 which emits light.Therefore, light emitted from LED may pass through the openings 132without any shielding or blocking.

The conductive foil 130 may be, but not limited to, a copper foil coatedwith silver. The openings 132 may be formed by punching or stamping on acopper foil.

Before S202, the method may comprise a pre-step: dispose the base layer120 b on a carrier (like 180 of FIG. 10) or on a work table.

In S204, please refer to FIG. 11B. The LED chips 102, 104 and theconductive electrodes 110, 112 are disposed on the conductive foil 130.As above-mentioned, the light emitting portions of the LED chips 102,104 are better to align with the openings 132.

Please refer to FIG. 11C. The electrical connection of S22 may beaccomplished by wire bonding process like that shown in FIG. 1. As shownin FIG. 11C, the LED chips 102, 104 and the conductive electrodes 110,112 are electrically connected together in series.

Next, please refer to FIG. 11D. Like the embodiment of FIG. 10, thelight conversion sub-layer may be referred to top layer 120 a. The toplayer 120 a fills out the gaps among the LED chips 102, 104 and theconductive electrodes 110, 112 including the gaps under the LED chips102, 104 and the openings 132.

Regarding the disposition of the top layer 120 a, there are a few methodto proceed with. The first one is to coat a mixture of the adhesive 122and the phosphors 124 on the LED chips 102, 104 and the conductiveelectrodes 110, 112. The second one is to firstly coat a layer ofadhesive 122 on the LED chips 102, 104 and the conductive electrodes110, 112, and secondly coat a layer of phosphors 124 on the layer of theadhesive 122 (two disposition steps). Thereafter, cure the layer ofadhesive 122 and the layer of phosphors 124. The third one is to repeatthe above two disposition steps until a required thickness is reached.Thereafter, a curing process is proceeded with. In comparison with thethree methods, the uniformity of the light conversion coating 120 doneby the third method might be better. Additionally, the disposition(coat) of the adhesive 122 or the phosphors 124 may be done by spraying.

After S24, a cut process may be proceeded with, referring to FIG. 11E.Cut LED filaments 100 are manufactured as shown in FIG. 11E.

In accordance with the embodiment of FIGS. 11A to 11E, the LED chips102, 104 and the conductive electrodes 110, 112 are electricallyconnected together through conductive foil 130 and conductive wire 140.The flexibility of the electrical connections is enhanced. Accordingly,when the LED filament 100 is bent, the electrical connections would notbe easily broken.

Please refer to FIGS. 12A and 12B which illustrate a perspective view ofLED light bulb applying the LED filaments according to a first and asecond embodiments. The LED light bulb 10 a, 10 b comprises a bulb shell12, a bulb base 16 connected with the bulb shell 12, at least twoconductive supports 14 a, 14 b disposed in the bulb shell 12, a drivingcircuit 18 electrically connected with both the conductive supports 14a, 14 b and the bulb base 16, and a single LED filament 100.

The conductive supports 14 a, 14 b are used for electrically connectingwith the conductive electrodes 110, 112 and for supporting the weight ofthe LED filament 100. The bulb base 16 is used to receive electricalpower. The driving circuit 18 receives the power from the bulb base 16and drives the LED filament 100 to emit light. Due that the LED filament100 emits light like the way a point light source does, the LED bulb 10a, 10 b may emit omnidirectional light. In this embodiment, the drivingcircuit 18 is disposed inside the LED light bulb. However, in someembodiments, the driving circuit 18 may be disposed outside the LEDbulb.

The definition of the omnidirectional light depends upon the area thebulb is used and varies over time. The definition of the omnidirectionallight may be, but not limited to, the following example. Page 24 ofEligibility Criteria version 1.0 of US Energy Star Program Requirementsfor Lamps (Light Bulbs) defines omnidirectional lamp in base-up positionrequires that light emitted from the zone of 135 degree to 180 degreeshould be at least 5% of total flux (lm), and 90% of the measuredintensity values may vary by no more than 25% from the average of allmeasured values in all planes (luminous intensity (cd) is measuredwithin each vertical plane at a 5 degree vertical angle increment(maximum) from 0 degree to 135 degree). JEL 801 of Japan regulates theflux from the zone within 120 degrees along the light axis should be notless than 70% of total flux of the bulb.

In the embodiment of FIG. 12A, the LED light bulb 10 a comprises twoconductive supports 14 a, 14 b. In an embodiment, the LED light bulb maycomprise more than two conductive supports 14 a, 14 b depending upon thedesign.

The bulb shell 12 may be shell having better light transmittance andthermal conductivity; for example, but not limited to, glass or plasticshell. Considering a requirement of low color temperature light bulb onthe market, the interior of the bulb shell 12 may be appropriately dopedwith a golden yellow material or a surface inside the bulb shell 12 maybe plated a golden yellow thin film for appropriately absorbing a traceof blue light emitted by a part of the LED chips 102, 104, so as todowngrade the color temperature performance of the LED bulb 10 a, 10 b.A vacuum pump may swap the air as the nitrogen gas or a mixture ofnitrogen gas and helium gas in an appropriate proportion in the interiorof the bulb shell 12, so as to improve the thermal conductivity of thegas inside the bulb shell 12 and also remove the water mist in the air.The air filled within the bulb shell 12 may be at least one selectedfrom the group substantially consisting of helium (He), and hydrogen(H₂). The volume ratio of Hydrogen to the overall volume of the bulbshell 12 is from 5% to 50%. The air pressure inside the bulb shell maybe 0.4 to 1.0 atm (atmosphere).

According to the embodiments of FIGS. 12A and 12B, each of the LED lightbulbs 10 a, 10 b comprises a stem 19 in the bulb shell 12 and a heatdissipating element 17 between the bulb shell 12 and the bulb base 16.The LED filament 100 is connected with the stem 19 through theconductive supports 14 a, 14 b. The stem 19 may be used to swap the airinside the bulb shell 12 with nitrogen gas or a mixture of nitrogen gasand helium gas. The stem 19 may further provide heat conduction effectfrom the LED filament 100 to outside of the bulb shell 12. The heatdissipating element 17 may be a hollow cylinder surrounding the openingof the bulb shell 12, and the interior of the heat dissipating element17 may be equipped with the driving circuit 18. The material of the heatdissipating element 17 may be at least one selected from a metal, aceramic, and a plastic with a good thermal conductivity effect. The heatdissipating element 17 and the stem 19 may be integrally formed in onepiece to obtain better thermal conductivity in comparison with thetraditional LED light bulb whose thermal resistance is increased duethat the screw of the bulb base is glued with the heat dissipatingelement.

Referring to FIG. 12A, the height of the heat dissipating element 17 isL1 and the height from the bottom of the heat dissipating element 17 tothe top of the bulb shell 12 is L2. The ratio of L1 to L2 is from 1/30to 1/3. The lower the ratio, the higher the cutoff angle of illuminationof the light bulb. In other words, the lower ratio increases the higherlight-emission angle and the light from the bulb is closer toomnidirectional light.

Please referring to FIG. 12B, the LED filament 100 is bent to form aportion of a contour and to form a wave shape. In order to appropriatelysupport the LED filament 100, the LED light bulb 10 b further comprisesa plurality of supporting arms 15 which are connected with and supportsthe LED filament 100. The supporting arms 15 may be connected with thewave crest and wave trough of the waved shaped LED filament 100. In thisembodiment, the arc formed by the filament 100 is around 270 degrees.However, in other embodiment, the arc formed by the filament 100 may beapproximately 360 degrees. Alternatively, one LED light bulb 10 b maycomprise two LED filaments 100 or more. For example, one LED light bulb10 b may comprise two LED filaments 100 and each of the LED filaments100 is bent to form approximately 180 degrees arc (semicircle). Twosemicircle LED filaments 100 are disposed together to form anapproximately 360 circle. By the way of adjusting the arc formed by theLED filament 100, the LED filament 100 may provide with omnidirectionallight. Further, the structure of one-piece filament simplifies themanufacturing and assembly procedures and reduces the overall cost.

In some embodiment, the supporting arm 15 and the stem 19 may be coatedwith high reflective materials, for example, a material with whitecolor. Taking heat dissipating characteristics into consideration, thehigh reflective materials may be a material having good absorption forheat radiation like graphene. Specifically, the supporting arm 15 andthe stem 19 may be coated with a thin film of graphene.

Please refer to FIG. 13A and FIG. 14A. FIG. 13A illustrates aperspective view of an LED light bulb according to a third embodiment ofthe present disclosure. FIG. 14A illustrates a cross-sectional view ofan LED light bulb according to a fourth embodiment of the presentdisclosure. According to the third embodiment, the LED light bulb 10 ccomprises a bulb shell 12, a bulb base 16 connected with the bulb shell12, two conductive supports 14 a, 14 b disposed in the bulb shell 12, adriving circuit 18 electrically connected with both the conductivesupports 14 a, 14 b and the bulb base 16, a stem 19, supporting arms 15and a single LED filament 100. The LED light bulb 10 d of the fourthembodiment is similar to the third embodiment illustrated in FIG. 13Aand comprises two LED filaments 100 a, 100 b arranged at the differentvertical level in FIG. 14A. The LED filaments 100 a, 100 b are bent toform a contour from the top view of FIG. 14A.

The cross-sectional size of the LED filaments 100, 100 a, 100 b is smallthan that in the embodiments of FIGS. 12A and 12B. The conductiveelectrodes 110, 112 of the LED filaments 100, 100 a, 100 b areelectrically connected with the conductive supports 14 a, 14 b toreceive the electrical power from the driving circuit 18. The connectionbetween the conductive supports 14 a, 14 b and the conductive electrodes110, 112 may be a mechanical pressed connection or soldering connection.The mechanical connection may be formed by firstly passing theconductive supports 14 a, 14 b through the through holes 111, 113 (shownin FIG. 1 and secondly bending the free end of the conductive supports14 a, 14 b to grip the conductive electrodes 110, 112. The solderingconnection may be done by a soldering process with a silver-based alloy,a silver solder, a tin solder.

Similar to the first and second embodiments shown in FIGS. 12A and 12B,each of the LED filaments 100, 100 a, 100 b is bent to form a contourfrom the top view of FIGS. 13A and 14A. In the embodiments of FIGS. 13A,14A, each of the LED filaments 100, 100 a, 100 b is bent to form a waveshape from side view. The shape of the LED filament 100 is novel andmakes the illumination more uniform. In comparison with a LED bulbhaving multiple LED filaments, single LED filament 100 has lessconnecting spots. In implementation, single LED filament 100 has onlytwo connecting spots such that the probability of defect soldering ordefect mechanical pressing is decreased.

The stem 19 has a stand 19 a extending to the center of the bulb shell12. The stand 19 supports the supporting arms 15. The first end of eachof the supporting arms 15 is connected with the stand 19 a while thesecond end of each of the supporting arms 15 is connected with the LEDfilament 100, 100 a, 100 b. Please refer to FIG. 13B which illustratesan enlarged cross-sectional view of the dashed-line circle of FIG. 13A.The second end of each of the supporting arms 15 has a clamping portion15 a which clamps the body of the LED filament 100, 100 a, 100 b. Theclamping portion 15 a may, but not limited to, clamp at either the wavecrest or the wave trough. Alternatively, the clamping portion 15 a mayclamp at the portion between the wave crest and the wave trough. Theshape of the clamping portion 15 a may be tightly fitted with the outershape of the cross-section of the LED filament 100, 100 a, 100 b. Thedimension of the inner shape (through hole) of the clamping portion 15 amay be a little bit smaller than the outer shape of the cross-section ofthe LED filament 100, 100 a, 100 b. During manufacturing process, theLED filament 100, 100 a, 100 b may be passed through the inner shape ofthe clamping portion 15 a to form a tight fit. Alternatively, theclamping portion 15 a may be formed by a bending process. Specifically,the LED filament 100, 100 a, 100 b may be placed on the second end ofthe supporting arm 15 and a clamping tooling is used to bend the secondend into the clamping portion to clamp the LED filament 100, 100 a, 100b.

The supporting arms 15 may be, but not limited to, made of carbon steelspring to provide with adequate rigidity and flexibility so that theshock to the LED light bulb caused by external vibrations is absorbedand the LED filament 100 is not easily to be deformed. Since the stand19 a extending to the center of the bulb shell 12 and the supportingarms 15 are connected to the stand 19 a, the position of the LEDfilaments 100 is at the level close to the center of the bulb shell 12.Accordingly, the illumination characteristics of the LED light bulb 10 care close to that of the traditional light bulb including illuminationbrightness. The illumination uniformity of LED light bulb 10 c isbetter.

In the embodiment, the first end of the supporting arm 15 is connectedwith the stand 19 a of the stem 19. The clamping portion of the secondend of the supporting arm 15 is connected with the outer insulationsurface of the LED filaments 100, 100 a, 100 b such that the supportingarms 15 are not used as connections for electrical power transmission.In an embodiment where the stem 19 is made of glass, the stem 19 wouldnot be cracked or exploded because of the thermal expansion of thesupporting arms 15 of the LED light bulb 10 c.

Since the inner shape (shape of through hole) of the clamping portion 15a fits the outer shape of the cross-section of the LED filament 100, theorientation of the cross-section of the LED filament 100, if necessary,may be properly adjusted. As shown in FIG. 13B, the top layer 120 a isfixed to face around ten o'clock direction such that illuminationsurfaces of the LED filament 100 are facing substantially the samedirection.

Please refer to FIG. 14B which illustrates the circuit board of thedriving circuit of the LED light bulb from the top view of FIG. 14Aaccording to the fourth embodiment of the present disclosure. Thedriving circuit 18 comprises a circuit board 18 a which is fixed to thebulb base 16. The conductive supports 14 a, 14 b are electricallyconnected with the circuit board 18 a and passes through the stand 19 ato be electrically connected with the conductive electrodes 110, 112 ofthe LED filament 100 a, 100 b. The circuit board 18 a comprises notches18 b. The notches 18 b are of hook shape. The size of the tip of thenotches 18 b is slightly smaller than that of the cross-section of theconductive supports 14 a, 14 b for fixing the conductive supports 14 a,14 b. The tip of the notches 18 b is beneficial to the soldering betweenthe circuit board 18 a and the conductive supports 14 a, 14 b.

In the embodiments of FIGS. 13A and 14A, the length of the conductivesupports 14 a, 14 b is better to meet the below equation to prevent twoconductive supports 14 a, 14 b from short circuit or to prevent theconductive supports 14 a, 14 b from unable to reach the circuit board 18a.L=A+√{square root over ( )}(

(B−3.2)

^2+H^2)

Wherein, referring to FIG. 14A, 3.2 is the electricity safety spacing; Lis the calculated length of the conductive supports 14 a, 14 b and itsunit is mini-meter; A is the sum of the thickness of the circuit board18 a and the height of the portion of the conductive supports 14 a, 14 bexposed from the surface of the circuit board 18 a; B is the horizontaldistance between the two conductive supports 14 a, 14 b; and H is theheight from the circuit board 18 a to the point the conductive supports14 a, 14 b enters the stem 19. The actual length of the conductivesupports 14 a, 14 b may be, but not limited to, between 0.5 L and 2 L,and more particularly between 0.75 L and 1.5 L.

In the embodiment of FIG. 14A, the LED light bulb 10 d has two LEDfilaments 100 a, 100 b disposed on different vertical levels. Theconductive supports 14 a, 14 b for the upper LED filaments 100 a has alength Z=L+Y. Y is the distance between the upper LED filament 100 a andthe lower LED filament 100 b.

While the instant disclosure related to an LED filament and LED lightbulb has been described by way of examples and in terms of the preferredembodiments, it is to be understood that the instant disclosure needsnot be limited to the disclosed embodiments. For anyone skilled in theart, various modifications and improvements within the spirit of theinstant disclosure are covered under the scope of the instantdisclosure. The covered scope of the instant disclosure is based on theappended claims.

What is claimed is:
 1. An LED light bulb, comprising: a bulb shell; abulb base connected with the bulb shell; and an LED filament disposed inthe bulb shell, the LED filament comprising: a plurality of LED chips,electrically connected together; two conductive electrodes, disposedcorresponding to the plurality of LED chips, the conductive electrodesbeing electrically connected with the plurality of LED chips; and aflexible light conversion coating, coating on each side of the LED chipsand a portion of the conductive electrodes, and exposing a portion ofthe conductive electrodes, and the flexible light conversion coatingcomprising an adhesive and a plurality of particles, wherein theplurality of particles comprises phosphors and nanoparticles and apercentage of the particles in the flexible light conversion coating isgreater than a percentage of the adhesive in the flexible lightconversion coating, wherein the flexible light conversion coatingfurther comprises at least one thermal conduction path formed by atleast a part of the phosphors and nanoparticles which are adjacent toand contact one another, the at least one thermal conduction path has aninternal end and an external end, the internal end of the at least onethermal conduction path contacts one of the LED chips, and the externalend of the at least one thermal conduction path contacts the surface ofthe flexible light conversion coating away from the LED chips and isexposed from the surface of the flexible light conversion coating. 2.The LED light bulb of claim 1, wherein the LED filament furthercomprises a plurality of conductive wires electrically andcorrespondingly connected among the plurality of LED chips and theconductive electrodes, the flexible light conversion coating coveringthe plurality of conductive wires.
 3. The LED light bulb of claim 2,wherein at least one of the plurality of conductive wires is of M shape.4. The LED light bulb of claim 1, wherein the LED filament furthercomprises a plurality of circuit films electrically and correspondinglyconnected among the plurality of LED chips and the conductiveelectrodes, wherein the flexible light conversion coating covering theplurality of the circuit films.
 5. The LED light bulb of claim 4,wherein each of the circuit films comprises a first film and aconductive circuit disposed thereon, and the conductive circuits areelectrically and correspondingly connected among the plurality of LEDchips and the conductive electrodes.
 6. The LED light bulb of claim 1,wherein the flexible light conversion coating comprises a base layer anda top layer, the plurality of LED chips are on a side of the base layer.7. The LED light bulb of claim 6, wherein the hardness of the base layeris higher than the hardness of the top layer.
 8. The LED light bulb ofclaim 1, wherein the LED filament further comprises a plurality ofconductive wires electrically and correspondingly connected among theplurality of LED chips and the conductive electrodes, the flexible lightconversion coating covering the plurality of conductive wires and eachside of each of the plurality of LED chips, at least one of theplurality of conductive wires being of M shape, wherein the flexiblelight conversion coating comprises a base layer and a top layer, theplurality of LED chips are on a side of the base layer, the hardness ofthe base layer is higher than the hardness of the top layer, a size ofthe nanoparticles is substantially smaller than a size of the phosphors,the composition ratio of the plurality of the phosphors to the adhesiveis between 1.5:1 or 50:1.
 9. The LED light bulb of claim 1, wherein theLED filament further comprises a plurality of circuit films electricallyand correspondingly connected among the plurality of LED chips and theconductive electrodes, the flexible light conversion coating coveringthe plurality of the circuit films, each of the circuit films comprisinga first film and a conductive circuit disposed thereon, and theconductive circuits electrically and correspondingly connected among theplurality of LED chips and the conductive electrodes, wherein theflexible light conversion coating comprises a base layer and a toplayer, the plurality of LED chips are on a side of the base layer, thehardness of the base layer is higher than the hardness of the top layer,a size of the nanoparticles is substantially smaller than a size of thephosphors, the composition ratio of the plurality of the phosphors tothe adhesive is between 1.5:1 or 50:1.
 10. The LED light bulb of claim1, wherein the percentage of the particles in the flexible lightconversion coating is a volume percentage or a weight percentage and thepercentage of the adhesive in the flexible light conversion coating is avolume percentage or a weight percentage.
 11. The LED light bulb ofclaim 1, wherein the size of the nanoparticles is substantially smallerthan the size of the phosphors.
 12. The LED light bulb of claim 11,wherein the thermal conduction path formed by at least a part of thephosphors and the nanoparticles which are adjacent to and contact oneanother.
 13. The LED light bulb of claim 1, wherein the flexible lightconversion coating further comprises at least two of the thermalconduction paths, the external end of one of the at least two thermalconduction paths contacts a first surface of the flexible lightconversion coating away from the LED chips and is exposed from the firstsurface of the flexible light conversion coating, the external end ofanother one of the at least two thermal conduction paths contacts asecond surface of the flexible light conversion coating away from theLED chips and is exposed from the second surface of the flexible lightconversion coating, the first surface and the second surface areopposite to each other, and one of first surface and the second surfaceis an illumination surface of the LED filament.
 14. An LED light bulb,comprising: a bulb shell; a bulb base connected with the bulb shell; andan LED filament disposed in the bulb shell, the LED filament comprising:a plurality of LED chips, electrically connected together; twoconductive electrodes, disposed corresponding to the plurality of LEDchips, the conductive electrodes being electrically connected with theplurality of LED chips; and a flexible light conversion coatingcomprising a top layer and a base layer, the flexible light conversioncoating coating on each side of the LED chips and a portion of theconductive electrodes, and exposing a portion of the conductiveelectrodes, the LED chips interposed between the base layer and the toplayer, wherein the top layer comprises a first adhesive and a pluralityof first particles and the base layer comprises a second adhesive and aplurality of second particles, the plurality of first particles at leastcomprises phosphors and a percentage of the plurality of first particlesin the top layer is greater than a percentage of the first adhesive inthe top layer, wherein the flexible light conversion coating furthercomprises at least one thermal conduction path formed by at least a partof the first or second particles which are adjacent to and contact oneanother, the at least one thermal conduction path has an internal endand an external end, the internal end of the at least one thermalconduction path contacts one of the LED chips, and the external end ofthe at least one thermal conduction path contacts the surface of theflexible light conversion coating away from the LED chips and is exposedfrom the surface of the flexible light conversion coating.
 15. The LEDlight bulb of claim 14, wherein the percentage of the plurality of firstparticles in the top layer is a volume percentage or a weight percentageand the percentage of the first adhesive in the top layer is a volumepercentage or a weight percentage.
 16. The LED light bulb of claim 15,wherein the plurality of first particles further comprises firstnanoparticles, and the size of the first nanoparticles is substantiallysmaller than the size of the first phosphors.
 17. The LED light bulb ofclaim 14, wherein the percentage of the plurality of second particles inthe base layer is a volume percentage or a weight percentage and thepercentage of the second adhesive in the base layer is a volumepercentage or a weight percentage.
 18. The LED light bulb of claim 17,wherein the plurality of second particles further comprises secondnanoparticles, and the size of the second nanoparticles is substantiallysmaller than the size of the second phosphors.
 19. The LED light bulb ofclaim 14, wherein the plurality of second particles at least comprisesphosphors and a percentage of the plurality of second particles in thebase layer is greater than a percentage of the second adhesive in thebase layer.
 20. The LED light bulb of claim 19, wherein the flexiblelight conversion coating further comprises at least two of the thermalconduction paths comprising a first thermal conduction path formed by atleast a part of the first particles which are adjacent to and contactone another and a second thermal conduction path formed by at least apart of the second particles which are adjacent to and contact oneanother, the external end of the first thermal conduction path contactsa first surface of the flexible light conversion coating away from theLED chips and is exposed from the first surface of the flexible lightconversion coating, the external end of the second thermal conductionpath contacts a second surface of the flexible light conversion coatingaway from the LED chips and is exposed from the second surface of theflexible light conversion coating, the first surface and the secondsurface are opposite to each other, and one of first surface and thesecond surface is an illumination surface of the LED filament.